I read this in a superuser.com question:
The problem is that "Advanced Format" drives that simulate a 512-byte sector to the operating system but actually work with 4-kilobyte sectors internally is that a sector can only be written "in one go". In order to write to that second 512 byte area the entire 4KB sector must be read, and then re-written back to the drive, and this is a slower process than simply telling the drive to rewrite the whole 4KB sector.
Why can a sector be only written "in one go" in "advanced format"?